Question

Can anyone shed any light on this issue please?

ASP.NET 4.0 / C#

The code:

Image image = Image.FromStream(Request.Files[0].InputStream);
var newWidth = 150;
var current = image.Width;
double scaleHeight = (150 / current);
if (scaleHeight == 0)
{
    scaleHeight = 0.2;
}
var newHeight = Convert.ToInt32(image.Height * scaleHeight);
var thumbnailBitmap = new Bitmap(newWidth, newHeight);
Graphics thumbnailGraph = Graphics.FromImage(thumbnailBitmap);

This code above always sets the scaleHeight as 0.2. Oddly the image.Width in the debugger is referencing the correct width of the image so logically 150 / x should give the decimal percentage 150 is of x, then I can workout a new height based on that percentage (height * result) – at least I think that’s the math! hehe.

Eg: 150/1024==0.1464. Then 768 * 0.1464 == 112 (int) – 14% of 768 is approx 112. This doesn’t work in the code – any ideas?

I’m clearly doing something stupidly wrong here, can anyone shed any light on this?

Sry for a daft question. Thanks for any help!

Chris.

Answer 1

This code above always sets the scaleHeight as 0.2

Careful with your var’s. image.Width is an integer, so you are performing integer division here:

(150 / current);

If current is larger than 150 the result will always be 0. The act of assigning the result to a double does not mean that the result was not obtained using integer division. Try this:

double scaleHeight = (150.0 / current);

Of course, it really should be this:

double newWidth = 150;
var current = image.Width;
double scaleHeight = (newWidth / current);

As a side note, the ‘var’ keyword is great for reducing unnecessary verbosity in your code. However, I wouldn’t get into the habit of declaring everything as ‘var’. For one, it only serves to make your particular code snippet less clear. Secondly, you aren’t really saving any typing (ok, a few more letters to type ‘double’, but you need that!). My advice would be to use ‘var’ only when it makes your code easier to read/understand due to there being less unnecessary verbosity. For simple things like declaring an int it isn’t necessary and doesn’t add any value.